diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 3ad65d8..d7de1c6 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -28,7 +28,5 @@ jobs:
       run: mkdir build; cd build; cmake ..
     - name: make
       run: cd build; cmake --build . -j -v
-    - name: macos-test
-      run: cd build; ./test_filter
-    #- name: test
-    #  run: cd build; ctest
+    - name: test
+      run: cd build; ctest
diff --git a/README.md b/README.md
index 50805fb..db805c8 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,11 @@ If you are on Unix systems, try
 mkdir build
 cd build
 cmake ..
+cmake --build .
 ```
 It requires compilers that support C++17 (gcc version >= 8, clang version >= 7, Apple Clang version >= 11.0, MSVC version >= 19.14).
 
-Apple M1 users: you might need to build Embree from scratch since the prebuilt MacOS binary provided is built for x86 machines.
+Apple M1 users: you might need to build Embree from scratch since the prebuilt MacOS binary provided is built for x86 machines. (But try build command above first.)
 
 # Run
 Try 
diff --git a/src/tests/matrix.cpp b/src/tests/matrix.cpp
index b455c16..e25d3dc 100644
--- a/src/tests/matrix.cpp
+++ b/src/tests/matrix.cpp
@@ -10,7 +10,6 @@ int main(int argc, char *argv[]) {
     );
     Matrix4x4 m_inv = inverse(m);
     Matrix4x4 m_inv_m = m_inv * m;
-    int count = 1;
     for (int i = 0; i < 4; i++) {
         for (int j = 0; j < 4; j++) {
             Real target = i == j ? Real(1) : Real(0);
@@ -18,7 +17,6 @@ int main(int argc, char *argv[]) {
                 printf("FAIL\n");
                 return 1;
             }
-            count++;
         }
     }